This invention relates to draw latches for latching together two closure members. The latch is referred to as a "draw latch" because it forceably draws together the two members on which the latch members are mounted. Such members may be components of a cabinet, or a case, or a housing for a machine, or any type of enclosure. In many cases, the closure members will be co-planar panels. But in other cases the two closure members will be angularly disposed, such as at right angles to each other.
All draw latches are basically toggle devices having three links and three pivot points. One of the pivot points is disengageable so that the latch may be unlatched to separate the closure members.
The present invention relates particularly to a draw latch of the toggle type which is adjustable. The adjustable feature is necessary, or at least desirable, because the latched members may have dimensional variations due to their method of manufacturing or because they may be subject to deformation in use. Usually the latched joint will include a gasket between the two closure members which will change in thickness or resilience in use due to age, environment, or other factors. The latch would require readjustment to properly seal the gasket.
The prior art has provided draw latches of the toggle type with means for adjusting the distance between latching points. Some prior art adjustable latches incorporate a screw thread in the link which is to be stressed in tension. This introduces an undesirable feature, namely, if the latch be loaded beyond its maximum holding strength, there would be a complete failure of the latch mechanism.
Also in some prior art adjustable draw latches, the threaded tension link is the detachable link and is articulated with the handle lever in such manner that the latching operation involves two motions: (1) engagement of the detached link with its cooperating element and (2) the lever action to close the latch. Depending on the orientation of the latch with respect to gravity or other outside forces, the latching operation may require two hands.
Another deficiency of prior art adjustable draw latches resides in the complexity of the mechanism due to the attachment of the link. Usually rivets and cross pins are required to provide the pivoting joint.
A further disadvantage of the prior art adjustable draw latch is the generally unpleasing appearance of the device. Due to the geometry of the articulated members, the mounting hardware and other aesthetically objectionable features are exposed to view.